Goof around
Definition 1 of 1
Pro Tip 1/3Informality
Used in casual, relaxed settings among friends or family, not formal situations. 
They were just goofing around backstage before the concert.
Pro Tip 2/3Non-productive
Implies time spent without achieving anything significant or with frivolity. 
I should have been studying, but I goofed around all weekend.
Pro Tip 3/3Light-heartedness
Conveys a sense of carefree fun or playful behavior that is not taken seriously. 
The team goofed around with a football after practice.